Sensors (e.g., linear and variable differential transducers), motors, and actuators (e.g., solenoids) commonly include one or more electromagnetic coils formed by wound magnet wire. In certain designs, the electromagnetic coils may be embedded within or encapsulated by a body of dielectric material, such as a potting compound, to provide position holding and electrical insulation between neighboring turns of the coils and thereby improve the overall durability of the coiled-wire device. The opposing ends of the magnet wire may project from the dielectric body to enable electrical connection between the potted electromagnetic coil and an external circuit or power source. In conventional, low temperature applications, the electromagnetic coil is typically embedded within an organic dielectric material, such as a relatively soft rubber or silicone, that has a certain amount of flexibility, elasticity, or compressibility. As a result, a limited amount of movement of the magnet wire at the point at which the wire enters or exits the dielectric body is permitted, which alleviates mechanical stress applied to the magnet wire during assembly and packaging of the coiled-wire device.
While low temperature electromagnetic coils are commonly potted with flexible dielectric materials of the type described above, this is not always the case. Instead, in certain instances, the electromagnetic coil or coils may be embedded within a material or medium that is relatively rigid, such as a hard plastic or certain inorganic materials. As a result, the magnet wire may be effectively fixed or anchored in place at the wire's entry point into or exit point from the dielectric body. Significant mechanical stress concentrations may thus occur at the wire's entry or exit point from the rigid dielectric body as the external portion of the magnet wire is subjected to unavoidable bending, pulling, and twisting forces during the assembly process. The magnet wire may consequently mechanically fatigue and work harden at this interface during assembly and packaging of the coiled-wire device. Work hardening of the magnet wire may result in breakage of the wire during assembly or the creation of a high resistance “hot spot” within the wire accelerating open circuit failure of the coiled-wire device during operation. Such issues are especially problematic when the coiled magnet wire has a relatively fine gauge (e.g., a gauge greater than about 30 American Wire Gauge) and/or is fabricated from a metal prone to work hardening and mechanical fatigue, such as aluminum.
There thus exists an ongoing need to provide embodiments of an electromagnetic coil assembly including a coiled magnet wire, such as a fine gauge aluminum magnet wire, which is at least partly embedded within a body of dielectric material and which is effectively isolated from mechanical stress during manufacture. It would further be desirable, at least in certain embodiments, if such electromagnetic coil assemblies where capable of providing continuous, reliable operation in high temperature applications (e.g., applications characterized by temperatures exceeding 260° C.), such as high temperature avionic applications wherein the electromagnetic coil assembly is integrated into a sensor, motor, actuator, or the like. Finally, it would be desirable to provide embodiments of a method for manufacturing such an electromagnetic coil assembly. Other desirable features and characteristics of the present invention will become apparent from the subsequent Detailed Description and the appended Claims, taken in conjunction with the accompanying Drawings and the foregoing Background.